Snares and nets are in widespread use for severing and retrieving tissue from patients, or subjects. The devices are used in human and anal subjects, in laparoscopic surgeries and other procedures where access to tissue is only possible via a small opening. One exemplary use is for cutting off and retrieving intestinal polyps where a wire snare, passed through an colonoscope instrument channel, encircles and is tightened about an intestinal polyp to sever the polyp. The severed polyp is retrieved in a net inserted through the instrument channel. The net is manipulated to enclose the polyp and then withdrawn with the instrument so that the tissue architecture remains undisturbed.
In this procedure, as well as others, the net and snare must be quite compact in order to pass into the subject through the instrument channel, or other passage. Prior art proposals have employed snares supported within plastic tubes that were snaked into the subject to locate the snare where desired. The snare was then deployed from its tube, manipulated to cut off the polyp and retrieved into the tube for removal from the subject.
A net, collapsed within another tube, was introduced through the instrument channel, etc., for removing the polyp. When near a target polyp, the net was deployed, like the snare, and manipulated to net the polyp. The net was then closed sufficiently to secure the polyp and withdrawn from the subject. These proposals required use of separate snare and net devices, which in turn complicated and lengthened surgeries by increasing the number of steps required. For various reasons, devices such as the snare and net devices are constructed for disposal after a single use. Disposal of multiple devices after a single use was not cost effective.
U.S. Pat. No. 5,290,542 discloses a combined snare and net device for removing tissue from a subject. There, the snare and net were contained in a common introducer tube, commonly actuated and fastened together in tandem. The snare and net were subject to becoming ensnarled during use. Moreover, manipulating the combined snare and net was unwieldy. The proposed device was not successful.
The present invention provides a new and improved surgical device for removing tissue from a subject wherein simultaneous introduction of a snare and a net into a subject is accomplished, with the snare and net being separated and individually deployed and retrieved so that they do not interfere with each other during the procedure. Improvements in the construction and operation of both the net and the snare are also provided.